Apple

Reviving a Late 2011 iMac: Clean Install of macOS High Sierra

/ John Wagenvoort / Leave a comment

Introduction

Today, we successfully completed a full clean installation of macOS High Sierra onto a Late 2011 iMac. The goal was to prepare the machine for gifting, leaving it at the Setup Assistant so the new owner experiences it like a new Mac. This blog post summarizes the journey, decisions, and technical steps taken.

Stage 1: Initial Problem

  • The iMac had a freshly erased internal HDD.
  • Attempted to install macOS Sierra from a standard installer.
  • Installation would nearly complete, then error out stating “An error occurred, please run the installer again.”

Key Suspicions

  • Potential hard drive aging issues.
  • Installer image corruption.
  • Time/date certificate issues.

Immediate Actions

  • Verified and corrected system date and time via Terminal.
  • Erased the drive properly using Disk Utility, ensuring:
    • Format: Mac OS Extended (Journaled)
    • Scheme: GUID Partition Map

Stage 2: Hurdles with macOS Sierra Installer

  • The available Sierra installer was an InstallOS.dmg, not a full Install macOS Sierra.app.
  • Due to being on a newer MacOS (Sequoia), the package inside could not be expanded or executed natively.
  • Decided that High Sierra would be a better solution due to its broader hardware support and smoother installation compatibility with Late 2011 iMacs.

Stage 3: Getting High Sierra Installer

  • Direct downloads from the App Store were blocked or incompatible.
  • Successfully used iBoysoft DiskGeeker to download a full macOS High Sierra installer.
  • Verified that the full installer (5.2-5.3GB) was obtained, not a stub.

Creating the USB Installer

  • Used DiskGeeker to create a bootable High Sierra USB stick.
  • Labeled and preserved the USB stick for future use.

Stage 4: Installation and Setup Preparation

  • Booted the iMac holding Option (Alt) key and selected the USB installer.
  • Used Disk Utility to:
    • Erase the internal drive properly.
    • Confirm format and scheme.
  • Installed macOS High Sierra cleanly.

Key Detail

  • Left the iMac at the Setup Assistant screen by pressing Command + Q and shutting down.
  • This ensures the new owner will experience the initial setup process themselves.

Final Reflection

This project showed that even older Macs can be revitalized with careful prep, the right tools, and a logical workflow. Understanding how newer macOS versions interact (or fail to interact) with legacy installers was key to success.

Key Takeaways

  • Always correct system date/time before installing older macOS.
  • Sierra installers via InstallOS.dmg are problematic under modern macOS.
  • High Sierra remains the best legacy installer for Late 2011 iMacs.
  • Leave gifted Macs at Setup Assistant for best “new user” experience.

Post Author: John Wagenvoort
Assisted by: Kai

New Life for 2011 MBP 17

/ John Wagenvoort / Leave a comment

Back in 2012 I purchased a refurbished MacBook Pro 17″ Unibody. (Refurbished due to the GPU having failed already but that’s another story)

This Macbook’s latest Apple supported OS was High Sierra. So some years ago already this machine was being passed by and less capable of running latest apps like Daylite and PDF Expert.

Along came dosdude1 with his sensational patcher for installing Catalina on an unsupported Mac. This allowed the MBP to continue being of useful service until last year when again Daylite and PDF Expert had passed it by.

So I bit the bullet this weekend and decided to give my MBP 17 an OpenCore Legacy Patcher – Sonoma xmas upgrade.

All I can say is that the entire process is so slick that it motivated me to write this.

If you have an old Mac and want to install a later or latest OS then check out; https://dortania.github.io/OpenCore-Legacy-Patcher/

Well worth a look.

Thanks to everyone at OpenCore.

The Apple didn’t fall far from the tree.

/ John Wagenvoort / Leave a comment

It would be a year ago that I delved into the world of Apple for the first time with my then not too highly thought of iPad. I remember going on about this that and the other. Hmmm, no USB ports etc. Well, a year on and it’s a totally different story.

Soon after the iPad had become the much needed commodity I just couldn’t do without, the Nokia E71 was soon supplanted with an iPone.

Now to just rewind a bit. I started working with the humble PC back in 1987. Lotus 123 was the program of choice and not soon there after I was working with MS Excel 1d. Back in those days windows had winders. The PC would boot up to a C prompt in less than a minute or so. Hmmm what ever happened to that? Not to digress too much, one of my latest forays into the PC world was by way of an Acer Aspire net book. Upgraded to 2gb of ram no less.

Imagine playing a 45rpm vinyl record at 33 and a third and you soon get the point. There’s not a lot of doing when it comes to those sorts of machines except for one thing, waiting. When it does eventually boot, Microsoft decides that the machine hasn’t quite been stuffed to the gills yet and implores you to install the much needed 23 critical updates. Restart required, and then when it finally boots up again Adobe will insist that you must have the latest version of their pdf reader or Flash. Around this time the “must have anti virus program” will decide it’s about time for a scan. Needless to say that if one was to liken the PC to a toaster, one would simply throw it out and buy a new one. So that’s exactly what I did,……

I bought a Mac.

The End